Wir2.5 LESSON

PLOTTING POINTS = JUST LIKE BATTLESHIP Notebook File

4-1 Coordinates and Scatter Plots Coordinate Plane = a grid formed by two numbers lines, one vertical, the other horizontal Ex: Axes = the 2 #lines that define a coordinate plane. The horizontal # line is the x-axis and the vertical # line is the y-axis Origin = the point where the x- and y-axes meet in a coordinate plane Quadrants = the four sections formed by the axes in a coordinate plane Ordered Pair = 2 #s used together to designate a particular point in a coordinate plane. The 1 st # is the x-coordinate and the 2 nd # is the y-coordinate. (x, y) example (2, -3): x = 2, y = 3 so go to the right 2 and down 3! Coordinates = the 2#s in an ordered pair

Scatterplot = real-life situation comparing relationship btwn 2 quantities & graph the pairs on a coordinate axis

Use the coordinate plane at the right to write the coordinates of each point. 1.) A 2.) B 3.) C 4.) D 5.) E 6.) F 7.) G 8.) H EXAMPLE 1 Name points in a coordinate plane

Graph each given point on the axes on your worksheet. 1.) J = (6, 2) 2.) K = (-3, -5) 3.) L = (-1, 5) 4.) M = (0, 5) 5.) N = (4, 0) 6.) P = (-5, 0) 7.) R = (-5, -3) 8.) S = (6, -1) EXAMPLE 2 Plot points in a coordinate plane

Make a table by substituting the domain values into the function. STEP 1 SOLUTION Graph the function y = 2x – 1 with domain –2, –1, 0, 1, and 2. Then identify the range of the function. EXAMPLE 3 Graph a function STEP 2 List the ordered pairs: (–2, –5), (–1, –3), (0, –1), (1, 1), (2, 3). Then graph the function. STEP 3 Identify the range. The range consists of the y -values from the table: –5, –3, –1, 1, and 3.

GUIDED PRACTICE for Examples 2 and 3 Plot the point in a coordinate plane. Describe the location of the point. 1. A(2, 5) 2. B(–1, 0) 3. C(– 2, –1) x-axis ANSWER Quadrant III ANSWER Quadrant I ANSWER 4. D(–5, 3) Quadrant II ANSWER

GUIDED PRACTICE for Examples 2 and 3 5. Graph the function y = – x + 2 with domain –6, –3, 0, 3, and 6. Then identify the range of the function. 1 3 range: 0, 1, 2, 3, and 4 ANSWER Plot the point in a coordinate plane. Describe the location of the point.

Graph a function represented by a table EXAMPLE 4 VOTING In 1920 the ratification of the 19 th amendment to the United States Constitution gave women the right to vote. The table shows the number (to the nearest million) of votes cast in presidential elections both before and since women were able to vote. Explain how you know that the table represents a function. a.a. Graph the function represented by the table. b.b. Describe any trend in the number of votes cast. c.c. Years before or since 1920 –12–8– Votes (millions)

Graph a function represented by a table EXAMPLE 4 SOLUTION The table represents a function because each input has exactly one output. a.a. To graph the function, let x be the number of years before or since Let y be the number of votes cast (in millions). b.b. The graph of the function is shown. In the three election years before 1920, the number of votes cast was less than 20 million. In 1920, the number of votes cast was greater than 20 million. The number of votes cast continued to increase in the three election years since c.c.

GUIDED PRACTICE for Example 4 6. The presidential election in 1972 was the first election in which 18 -year-olds were allowed to vote. The table shows the number (to the nearest million) of votes cast in presidential elections both before and since VOTING Years before or since 1972 –12–8– Votes (millions) a. Explain how you know the graph represents a function. The table represents a function because each input has exactly one output. ANSWER

GUIDED PRACTICE for Example 4 b. Graph the function represented by the table. ANSWER c. Describe any trend in the number of votes cast. Sample answer: Before 1972, the number of votes cast increased by 2 million every 4 years. In 1972, the number increased by 5 million and continued to increase by more than 2 million every four years since ANSWER

Summary In the ordered pair (4,9), the x-coordinate is Ans: x is 4, y is 9 Decide whether the following statement is true or false. Each point in a coordinate plane corresponds to an ordered pair of real numbers. Ans: True Write the ordered pairs that correspond to the points labeled A, B, and C in the coordinate plane at the right. Ans: A = (1,1) B = (-2,1) c = (0, -2)

Check Yourself Pg #4-12e, 13-18, 23,24, 26, 36, Extra credit: - Graphiti drawing with points plotted and colored in! - Battleship game